5 DIM A(6,7),Z(6,6)
10 PRINT "INPUT N":INPUT N  
20 PRINT "INPUT MATRIX" 
30 FOR S=1 TO N 
40 INPUT A(S,1),A(S,2),A(S,3),A(S,4),A(S,5),A(S,6),A(S,7) 
60 Z(S,S)=1:NEXT S 
70 FOR S=1 TO N 
80 FOR T=S TO N:IF A(T,S)<>0 THEN 100:NEXT T  
90 PRINT "MATRIX SINGULAR":GOTO 999  
100 GOSUB 500
110 C=1/A(S,S):GOSUB 600 
120 FOR T=1 TO N:IF T=S THEN 140 
130 C=-A(T,S):GOSUB 700  
140 NEXT T:NEXT S:GOTO 800  
500 FOR J=1 TO N  
510 B=A(S,J): A(S,J)=A(T,J): A(T,J)=B
520 B=Z(S,J): Z(S,J)=Z(T,J): Z(T,J)=B
530 NEXT J:RETURN 
600 FOR J=1 TO N  
610 A(S,J)=C*A(S,J): Z(S,J)=C*Z(S,J) 
620 NEXT J:RETURN 
700 FOR J=1 TO N  
710 A(T,J)=A(T,J)+C*A(S,J): Z(T,J)=Z(T,J)+C*Z(S,J) 
720 NEXT J:RETURN 
800 PRINT 
810 FOR I=1 TO N:FOR J=1 TO N  
820 PRINT Z(I,J),:NEXT J:PRINT :NEXT I
999 END 

